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From "Daniel Barclay (Drill) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-2420) Identify and fix DatabaseMetaData.getColumns() bugs [umbrella/tracking bug]
Date Thu, 12 Mar 2015 01:13:38 GMT

    [ https://issues.apache.org/jira/browse/DRILL-2420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14357918#comment-14357918
] 

Daniel Barclay (Drill) commented on DRILL-2420:
-----------------------------------------------

For reference re JDBC specification (Javadoc) ambiguity: 
[http://hsqldb.org/doc/src/org/hsqldb/jdbc/JDBCResultSetMetaData.html]
[http://hsqldb.org/doc/src/org/hsqldb/jdbc/JDBCDatabaseMetaData.html]

> Identify and fix DatabaseMetaData.getColumns() bugs [umbrella/tracking bug]
> ---------------------------------------------------------------------------
>
>                 Key: DRILL-2420
>                 URL: https://issues.apache.org/jira/browse/DRILL-2420
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Client - JDBC, Metadata
>            Reporter: Daniel Barclay (Drill)
>            Assignee: Daniel Barclay (Drill)
>
> Drill's implementation of {{DatabaseMetaData.getColumns(...)}} (currently at {{org.apache.drill.jdbc.MetaImpl.getColumns()}})
doesn't match the JDBC specification (the Javadoc documentation for {{DatabaseMetaData.getColumns(...)}}
(as of Java 7)).  In the returned {{ResultSet}}:
> 1. Column {{DATA_TYPE}} is of type {{VARCHAR}} (containing the type name) rather than
being of type {{INTEGER}} (containing values per {{java.sql.Types.*}}).
> 2. Column {{TYPE_NAME}} is missing.
> 3. Column {{COLUMN_SIZE}} is missing.
> 4. (Columns after {{DATA_TYPE}} are at incorrect indexes.)
> 5. Column {{DECIMAL_DIGITS}} is misnamed {{DECIMAL_PRECISION}}.
> 6. Column {{REMARKS}} is an empty string, but probably should be {{NULL}}.
> 7. Column {{COLUMN_DEF}} is an empty string, but probably should be {{NULL}}.
> 8. Column {{CHAR_OCTET_LENGTH}} is always {{4}}, but should be "the maximum number of
bytes in the _column_" for character types .
> 9. Column {{ORDINAL_POSITION}} is always {{1}}, but should be the index of the specific
column.
> 10. Column {{IS_NULLABLE}} is {{'YES'}}, which doesn't seem to correspond to the value
for {{NULLABLE}} ({{DatabaseMetaData.columnNullableUnknown}}).
> 11. Column {{SCOPE_CATALOG}} is an empty string, but should be {{NULL}}.
> 12. Column {{SCOPE_SCHEMA}} is an empty string, but should be {{NULL}}.
> 13. Column {{SCOPE_TABLE}} is an empty string, but should be {{NULL}}.
> 14. Column {{SOURCE_DATA_TYPE}} is an empty string, but should be {{NULL}}.
> Additional bugs or suspect behavior:
> - {{DECIMAL_DIGITS}}/{{DECIMAL_PRECISION}} is {{-1}} when it should be {{NULL}} (when
not applicable).
> - {{NUM_PREC_RADIX}} is {{-1}} when it probably should be {{NULL}} (when not applicable).
> (Other columns to check:
> Re {{BUFFER_LENGTH}}, {{SQL_DATA_TYPE}}, and {{SQL_DATETIME_SUB}}:  When JDBC says a
column is not used, are there any requirements on the values (e.g., being {{NULL}})? 
> Re {{IS_AUTOINCREMENT}}:  Do we know that a column is not auto-incremented?  If so, the
value could be {{'NO'}} rather than an empty string.
> Re {{IS_GENERATEDCOLUMN}}:  Do we know that a column is not generated?  If so, the value
could be {{'NO'}} rather than an empty string.
> Re {{NULLABLE}} (and {{IS_NULLABLE}}):  Do know whether a column is nullable or not?
 If so, we could return the specific answer rather that just saying that it's unknown.
> )



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